You are misinterpreting that argument. To prove copyrightability, Oracle had to show that designing an API is a creative act and not a purely mechanical/functional one. That is the purpose of this argument: if the function would only work if named java.lang.Math.max and not work if named Math.maximum, then anyone describing the same concept would be forced to use the same name, so the name wouldn't be copyrightable. They are not stating that Google would have been in the clear if they had named it differently, they are just trying to show that Google could have named it differently without changing the meaning of the code one iota.
For example, someone writing a recipe for omelette has to say "2 eggs" simply because that's what omelette needs. You can't express it any other way, so it's not a creative act, so it can't be protected by copyright.
For example, someone writing a recipe for omelette has to say "2 eggs" simply because that's what omelette needs. You can't express it any other way, so it's not a creative act, so it can't be protected by copyright.